Release stop means for pneumatic nail driving or stapling device

ABSTRACT

A release block or stop means for use with a pneumatically operated nail driving or stapling device comprises a slidable actuating member or slip-on part slidable in the direction it is slipped or installed on the device. The part protrudes from its position of rest beyond the mouthpiece of the device. Placing both the slip-on part and a release or tripping lever in operating position actuates a valve tappet mounted above an auxiliary member for causing a working stroke of the pneumatically operated nail driving device. Said auxiliary member is non-slidable, but has bushings slidably mounted thereon, the first of said bushings being coupled to the release lever and the second of said bushings being coupled to the slip-on part.

[ Mar. 12, 1974 RELEASE STOP MEANS FOR PNEUMATIC NAIL DRIVING OR STAPLING DEVICE [75] Inventor: Wilfned' Lange, Altenhagen,

Germany [73] Assignee: Bukama GmbH, Hannover, Germany [22] Filed: June 26, 1972 [21] Appl. No.: 266,491

[30] Foreign Application Priority Data June 26, 1971 Germany 2131849 [52] US. Cl 173/15, 91/461, 227/6 [51] Int. Cl B27f 7/22 [58] Field of Search 173/2, 15;'91/461; 227/6 [56] References Cited I UNITED STATES PATENTS 2,854,953 10/1958 Osborne 173/2 3,685,396 8/[972 Obergfell 91/461 X 3,677,456 7/1972 Ramspeck 91/461 X Primary Examiner-Emest R. Purser Attorney, Agent, or Firm-Hibben, Noyes & Bicknell ABSTRACT A release block or stop means for use with a pneumatically operated nail driving or stapling device comprises a slidable actuating member or slip-on part slidable in the direction it is slipped or installed on the device. The part protrudes from its position of rest beyond the mouthpiece of the device. Placing both the slip-on part and a release or tripping lever in operating position actuates a valve tappet mounted above an auxiliary member for causing a working stroke of the pneumatically operated nail driving device. Said auxiliary member is non-slidable, but has bushings slidably mounted thereon, the first of said bushings being coupled to the release lever and the second of said bushings being coupled to the slip-on part.

6 Claims, 5 Drawing Figures ,19 L5 u. 15 1B 16 25 2b 2& 26

PAIENTEUMR12 new 3796; 270

SHEEI 2 OF 3 RELEASE STOP MEANS FOR PNEUMATIC NAIL DRIVING OR STAPLING DEVICE DESCRIPTION This invention relates to a release block or stop means used with a pneumatically operated nail driving or stapling device having a slip-on part which is slidable in its slip-on direction and protrudes in its position of rest beyond the mouthpiece of the device. The slip-on part in conjunction with a release or tripping lever when both are placed in an operating position actuates with an auxiliary member a valve tappet co-axially aligned to initiate a working stroke of the pneumatically operated nail driving device. The valve tappet defines with the auxiliary member an air space communicating with a pressurized air reservoir.

In the US. Pat. No. 3,490,545 there is disclosed a prior art release stop which comprises an auxiliary piston forming the upper part of the slip-on portion and being coupled via a double arm elbow lever to a superposed valve. When the slip-on part and/or the release lever are not in operating position, the superposed valve connects an air chamber between the auxiliary piston and a valve tappet with the reservoir of pressurized air. The air chamber is vented only when the slipon part and the release lever are in operating position, and only after the venting of said air chamber does the valve tappet initiate the working stroke of the pneumatic nail driver. Utilizing a special superposed valve as well as having the auxiliary piston as part of the slipon part produces a release stop arrangement which is costly and cumbersome and does not permit said release stop to be subsequently installed in an already existing pneumatic nail driving device.

The basic objective of the invention is to provide a release stop or blocking device such that the aforementioned disadvantages are avoided and that permits subsequent installation on a pneumatic nail driving device whereby a rapid mode of operation is achieved.

The release stop according to the invention comprises the improvements of an auxiliary member located in a portion of a housing or case bore so as to be non-slidable therein, the bore also a valve tappet controlling the working stroke of the pneumatic nail driving device. No special superposed valve is necessary and simplification of the structure is obtained. The improvement permits subsequent installation to be easily performed without any difficulty in pneumatic nail driving devices having a valve tappet controlling the working stroke thereof.

According to another feature of the invention, the auxiliary member is provided with two sleeves or bushings slidably mounted independently of each other, the first bushing being coupled to the release lever and the second bushing being coupled to the slip-on part. In this connection, the air chamber above the auxiliary member is in constant communication via a channel in the valve tappet with the pressured air reservoir. The air chamber can be connected via channels in the auxiliary member to a control chamber located in the first bushing and to a venting channel provided in the second bushing. The air chamber can be vented and the valve tappet may reach its downward position for initiating the working stroke of the pneumatic nail driving device only when both the release lever and the slip-on part are in operating position. In all other positions as well as when not in operation, pressure in the air chamber due to its permanent communication with the pressurized air reservoir holds the valve tappet in its upper position to prevent a working stroke.

In order to assure that the valve tappet is raised immediately after having reached its lower position preparatory to the next working stroke and to block the supply of pressured air to the working cylinder for the last working stroke, it is recommended to connect the air. chamber between the valve tappet and the auxiliary member through a throttling channel to the pressurized air reservoir so as to provide a definite time lapse before sufficient pressure is built up in said air chamber to raise the valve tappet. The throttling means is most suitably provided with a nozzle, preferably of the changeable type, such that the time to raise the valve tappet may be adjusted to different operating conditions of the nail driving device.

Additional features of the invention are explained hereinafter in conjunction with the drawing showing an embodiment according to the invention, wherein:

FIG. 1 is a partial sectional view, of a nail driving device when not in use;

FIG. 2 is a view of FIG. 1 with the slip-on part and the release lever in the non-operating position;

FIG. 3 is a view similar to FIG. 2, but with the slip-on part in non-operating position and the release lever in operating position;

FIG. 4 is a view similar FIG. 2, but with the slip-on part in operating position and the release lever in nonoperating position, and

FIG. 5 is view similar to FIG. 2, but with the slip-on part and the release lever in operating positions for, i.e. in the position actuating a working stroke of the nail driving device.

In FIG. I is illustrated a nail driving device used for driving nails or staples into a work piece (not illustrated). The device has a body or housing 1 made of a material such as light metal and comprises a handle 2 enclosing a reservoir 3 for pressurized air connected to a source of compressed air (not shown). In the front portion body I there is mounted a working cylinder 4 in which is slidably mounted a piston 5. The piston 5 drives a plunger or rod 6 which separates, during the working stroke, a staple from a bar of staples introduced into magazine 7 and which drives said staple through an ejector channel 9 located in a mouthpiece 8 into a work piece (not shown).

The working stroke of the pneumatically operated nail driver or stapler is actuated by a valve stem or tappet l0 traversing the air reservoir 3 and carrying a control valve 11 on the upper portion thereon. The valve 11 controls, in a manner will known, the piston-type intake valve 12 for the working cylinder 4. In the upper position of the valve 11, shown in FIG. 1, the intake valve 12 is closed and the piston 5 is in its initial position abutting the housing cover 13.

The valve tappet 10 is provided on its lower end with an enlargement 14 having the cylindrical end 15. The end 15 is received in a bore 16 of the housing, and the bore' 16 also receives the upper end of an auxiliary member 17 non-slidably mounted therein. Between this member 17 and the cylindrical end portion 15 the bore 16 of the housing forms an air chamber or space 18 permanently communicating, via a radial bore 19 (FIG. 1,), as well as the axial bore 20 of the valve tappet and- /or its enlargement 14 and a nozzle 21 mounted in the cylindrical end portion 15, with the pressurized air reservoir 3. As long as there is pressure in the air space 18, the valve tappet 10 is held in the upper position'shown in FIG. I so that the intake valve 12 of the working cylinder 4 is kept closed.

The lower portion 22 of the auxiliary member 17 is received in the bore 16 and is non-slidable therein. The member 17 is provided with a sleeve or bushing 23 slidably mounted thereon. The bushing 23 has on its upper end an annular groove 24 which is engaged by the release lever 26 which is pivotablymounted on a horizontal stud 25. Below the bushing 23 there is mounted a second sleeve or bushing 27 independent thereof and slidable on the lower cylindrical part 22 of the auxiliary member 17. This bushing 27 is provided with an annular groove 28 engaged by a structural member 29, the lower end 30 of which engages an oblong hole 31 at the upper end of the actuating member or slip-on part 32. The other end of the slip-on part 32 is bent at a right angle and carries a rest 33 acted on by a biasing spring 34 and is connected to a downwardly projecting foot 35.

The lower end of the cylindrical part 22 engages a hole 36 provided on the upper side of the magazine 7. The upper portion of the auxiliary member 17 is fixedly mounted with respect to the housing 1 by means of a retainer ring (FIG. 2). The upper portion of the auxiliary member 17 is provided with a turned groove 38 in open communication with the air space 18 via a radial bore 39 and an axial bore 40. The groove 38 is sealed with respect to bushing 23 by means of an upper O-ring 41 and a lower O-ring 42. The bushing 23 is provided underneath O-ring 42 with an annular groove 43 which is sealed at its top by O-ring 42 and at its bottom by O- ring 44. The lower auxiliary member part 22 is provided with :1 turned groove 45 communicating, via both radial bores 46 and 47 and an axial bore 48 interconnecting the latter bores, with the annular groove 43.

The turned groove 45 is sealed off by O-ring 49 at the top and by O-ring 50 at the bottom, the lower end of said bushing being provided with radial venting bores I.

The mode of operation is as follows:

As long as the air space 18 above auxiliary member 17 is exposed via channels 19, 20 and the nozzle 21 to the pressurized air in the reservoir 3 the valve tappet is held in the upper position shown in FIG. ll, wherein the control valve 11 holds the intake valve 12 in closed position and piston 5 remains in its upper initial position. In order to open the intake valve 12 it is necessary to vent the air space 18 so that the stapling or nail driving device can perform a working stroke. The air space 18 can be vented only' when both the bushings 23 and 27 slidably mounted on the lower part 22 of the auxiliary member 17 are moved to the proper position by movement of the release lever 26 and the slip-on part 32.

With only the release lever 26 pivoted into its operating position, the bushing 23 coupled thereto is lifted into the position shown in FIG. 3, but'the lower bushing 27 coupled to the slip-on part 32 is still retained in its initial position. As shown in FIG. 3, raising only the upper bushing 23 does not vent the air space 18 above the auxiliary member 17 since the annular groove 43 of bushing 23 communicating therewith is communicating via channels 46, 48, 47 with the annular groove 45 at the lower end of the auxiliary member part 22, which is still sealed by means of the O-ring 50 to prevent venting through bores 51.

If only the slip-on part 32 is placed on the work piece to be stapled, but the release lever 26 remains in its position of rest, as shown in FIG. 4, the lower bushing 27 is raised by the upper end 29 of slip-on part 32 guided in the oblong hole 31. This is best exemplified by the illustration of FIG. 4. In this position the venting bores 51 are open and in the same radial plane as the lower radial bore 47; however, the annular groove 43 of the upper bushing 23 is sealed from the radial bore 39 by means of the O-ring seal 42 so that no venting takes place. Therefore, it is not sufficient for initiating a work stroke to merely place thenail driving or stapling device on the work piece without actuating the release lever 26.

Only if both conditions are met, i. e. when both the slip-on part 32 as well as the release lever 26 arein the operating position shown in FIG. 5, is the air space 18 above the auxiliary piston 17 vented, via the axial bore 40, radial bore 39, annular groove 43, radial bore 46, axial bore 48 and radial bore 47, the lower annular groove 45, and the bores 51. When the air space 18 above the auxiliary member 17 is vented, the valve tappet 10 may move in a downward direction due to the air pressure in the pressured air reservoir 3 acting on the conical circular area of the enlargement 14, and the intake valve 12 is opened by the control valve 11.

After the working stroke of the pneumatic stapler has been completed it is possible to trigger a new stroke only when the air pressure in the air space18 has risen sufficiently so as to raise the valve tappet 10. The time required to raise the tappet is a function of the size of the bores 19, 20 and nozzle 21 and the rate the air flows into said air space 18. By exchanging the nozzle 21 adaptation to the various operating conditions is possible.

Since the air space 18 is relatively small and may be evacuated quickly, it is possible to achieve a' rapid mode of operation of the pneumatic stapling or nail driving device. The pneumatic control system used in accordance with the invention provides a number of advantages as opposed to the prior art mechanical device and may be subsequently installed, without any difficulties, on existing devices to equip them with a reliable stop means.

What I claim is:

l. A release stop means for a pneumatically operated stapling device having a housing forming a pressurized air reservoir, a piston and cylinder contained in the housing, a cylinder valve at an end of the cylinder, a mouthpiece through which staples are ejected, an actuating member extending in a rest position beyond the mouthpiece and being movable into operating position by being pressed against a work piece, and manual release lever means located on said housing; said release stop means comprising a control valve stem slidably located in an opening in said housing for pneumatically operating the cylinder valve, an auxiliary member fixedly located in said opening'below said valve stem, an air chamber formed between said auxiliary member and said valve stem, first and second sleeves slidably mounted on said auxiliary member, said first sleeve being connected to the release lever means and said second sleeve being connected to the actuating member, said first sleeve having a control space, said second sleeve having vent channel means, first passage means in said valve stem connecting said air chamber to said pressurized air reservoir, and second passage means within said auxiliary member for connecting said air chamber to said control space upon actuation of said release lever means and for connecting said control space to said vent channel means upon movement of 5 said actuating member to operating position, thereby venting said air chamber to permit movement-of said valve stem to actuate the cylinder valve and initiate a working stroke.

2. The release stop means according to claim 1, wherein said first passage means further comprises a nozzle throttling means.

3. The release stop means according to claim 2, wherein said nozzle throttling means is changeable to permit altering the speed of the device.

4. A release stop means for a pneumatically operated stapling device having a housing containing a pressurized air reservoir, a piston and cylinder, an actuating member extending below said device and being movable into operating position by being pressed against a work piece, and manual release lever means; said release stop means comprising a control valve stem'slidable in said housing for initiating a working stroke, an

auxiliary member fixedly located in said housing and forming an air chamber with said valve stem, a pair of sleeves slidably mounted on said auxiliary member, said first sleeve being connected to the release lever means and said second sleeve being connected to the actuating member,-one of said sleeves having a control space, and the other of said sleeves having vent means, first passage means in said device connecting said air chamber to said pressurized air reservoir, and second passage means in said device for connecting said air chamber to said control space and for connecting said control space to said vent means upon operation of said release lever means and actuating member, thereby venting said air chamber to permit movement of said valve stem to initiate a working stroke.

5. The release stop means according to claim 4, wherein said first passage means further comprises a nozzle throttling means.

6. The release stop means according to claim 4, wherein said nozzle throttling means is changeable to permit altering the speed of the device. 

1. A release stop means for a pneumatically operated stapling device having a housing forming a pressurized air reservoir, a piston and cylinder contained in the housing, a cylinder valve at an end of the cylinder, a mouthpiece through which staples are ejected, an actuating member extending in a rest position beyond the mouthpiece and being movable into operating position by being pressed against a work piece, and manual release lever means located on said housing; said release stop means comprising a control valve stem slidably located in an opening in said housing for pneumatically operating the cylinder valve, an auxiliary member fixedly located in said opening below said valve stem, an air chamber formed between said auxiliary member and said valve stem, first and second sleeves slidably mounted on said auxiliary member, said first sleeve being connected to the release lever means and said second sleeve being connected to the actuating member, said first sleeve having a control space, said second sleeve having vent channel means, first passage means in said valve stem connecting said air chamber to said pressurized air reservoir, and second passage means within said auxiliary member for connecting said air chamber to said control space upon actuation of said release lever means and for connecting said control space to said vent channel means upon movement of said actuating member to operating position, thereby venting said air chamber to permit movement of said valve stem to actuate the cylinder valve and initiate a working stroke.
 2. The release stop means according to claim 1, wherein said first passage means further comprises a nozzle throttling means.
 3. The release stop means according to claim 2, wherein said nozzle throttling means is changeable to permit altering the speed of the device.
 4. A release stop means for a pneumatically operated stapling device having a housing containing a pressurized air reservoir, a piston and cylinder, an actuating member extending below said device and being movable into operating position by beiNg pressed against a work piece, and manual release lever means; said release stop means comprising a control valve stem slidable in said housing for initiating a working stroke, an auxiliary member fixedly located in said housing and forming an air chamber with said valve stem, a pair of sleeves slidably mounted on said auxiliary member, said first sleeve being connected to the release lever means and said second sleeve being connected to the actuating member, one of said sleeves having a control space, and the other of said sleeves having vent means, first passage means in said device connecting said air chamber to said pressurized air reservoir, and second passage means in said device for connecting said air chamber to said control space and for connecting said control space to said vent means upon operation of said release lever means and actuating member, thereby venting said air chamber to permit movement of said valve stem to initiate a working stroke.
 5. The release stop means according to claim 4, wherein said first passage means further comprises a nozzle throttling means.
 6. The release stop means according to claim 4, wherein said nozzle throttling means is changeable to permit altering the speed of the device. 